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What is a Beam Width, Beam Size, and a Beam Waist?

Posted on 2007-07-11 as a part of the Photonics Spotlight (available as e-mail newsletter!)

Permanent link: https://www.rp-photonics.com/spotlight_2007_07_11.html

Author: , RP Photonics Consulting GmbH

Abstract: This article explains the origins of frequently encountered confusion concerning quantitative measures of the transverse extension of laser beams. Particular problems arise from the inappropriate use of terms such as beam size, waist size, beam width, and beam waist.

Dr. Rüdiger Paschotta

Ref.: encyclopedia articles on beam radius and beam divergence

Scientists as well as engineers are expected to communicate clearly, minimizing the risk of misunderstanding. Surprisingly, certain wordings, which constantly cause confusion, are very abundant in the scientific and technical literature. Some of those are related to the transverse extension of laser beams:

So my suggestion is to avoid a lot of confusion by making precise statements on all quantitative aspects of laser beams. Even in scientific papers, one all too often finds oneself in a situation where one has to construct sophisticated theories concerning what the author might have meant.

This article is a posting of the Photonics Spotlight, authored by Dr. Rüdiger Paschotta. You may link to this page and cite it, because its location is permanent. See also the RP Photonics Encyclopedia.

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